Nitrate contamination in groundwater

The BGS used cored boreholes to obtain profiles of the unsaturated zone pore water nitrate concentration as a function of depth in work pioneered in the 1970s.

Nitrate contamination of groundwater has long been recognised as an important public health issue.

Sources of nitrate in groundwater

The majority of nitrate in groundwater in the UK is derived from diffuse pollution from agriculture, with the rest from sewage sludge disposal to land, atmospheric deposition and point sources.

The loading has significantly increased due to post-1945 agricultural intensification due both to ploughing of grassland and to increased fertiliser applications.

Nitrate moves slowly through the unsaturated zone

Figure 1 pore water nitrate profiles (Chilton et al., 1991).

Pioneering work was done in the 1970s to understand how different UK land-use practices affected nitrate leaching to groundwater and how nitrate moves through the unsaturated zone of the major aquifers.

The BGS used cored boreholes to obtain profiles of the unsaturated zone pore water nitrate concentration as a function of depth.